Wooden stairs have been used for many, many years on all types of residential and some commerical construction. The standard closed stairs consists of two parallel spaced-apart members, called housings or stringers, which support a sufficient number of treads and risers to span the distance between the two levels for which the stairs are designed. The conventional method of producing the components for the stairs is to use a router and a jig to machine in the stringers each groove for a riser and a tread. There are known and commonly used various jigs and other devices which are designed to assist in locating the grooves in the stringers and to provide a guide for the router used to cut the grooves. However, these jigs and other devices are somewhat complicated and some of them are inconvenient to use. In any event, the carpenter generally has to make some relatively time consuming computations in order to determine both the rise and run of the stairs. In addition, the devices known and presently used will allow the router to cut only a single groove at a time, and then the device or jig has to be moved and properly positioned for the next groove. Moreover, in conventional stairs, the grooves are generally tapered to allow for proper and accurate final positioning of the treads and risers relative to each other with wedges being used to hold the treads and risers in place once they have been properly positioned. As a result, production of stairs even in a manufacturing facility is a slow process and subject to errors. The process is an even slower one where the stairs are constructed on the job site.
In my copending United States patent application, Ser. No. 874,413, filed Feb. 2, 1978, and entitled "Stairs and Method of Making the Same" I have disclosed a stairs construction using interlocking components that eliminate the use of wedges, adhesives and other fastening devices commonly employed in the manufacture of the conventional wooden stairs. The stairs construction disclosed in my said copending United States patent application requires accurate machining for which conventional methods and apparatus are not suitable. In addition, there is not known in the prior art any satisfactory apparatus or method for making the conventional glue-wedge type stairs on even a limited mass production basis. Therefore, the labor as well as material cost for conventional wooden stairs continues to increase. There is therefore a need for a method and apparatus for producing wooden stairs, both conventional and of the interlocking type disclosed in my said copending patent application, that will reduce the labor involved in producing such stairs and thus reduce the cost thereof. The method and apparatus of my invention as described herein greatly reduces the layout, production and assembly time of any wooden stairs and also practically eliminates the possibility of errors in the manufacture of such stairs.